Damper and heater control system



March 31, 1953 Filed June 25. 1949 L. P. BROWN, JR

2,633,299 DAMPER AND HEATER CONTROL SYSTEM 3 Sheets-Sheet l STAcK.CONTROL. 6 6

a a L 65 a INVENTOR.

25 LINN P. BROWN JR. BY hfiwdar/d ATTORNEYS March 31, 1953 BROWN, JR2,633,299

DAMPER AND HEATER CONTROL SYSTEM Filed June 23, 1949 3 Sheets-Sheet 2INVENTOR. LINN P. aaowu JR.

By W

ATTORNEYS March 1953 L. P. BROWN, JR 2,633,299

DAMPER AND HEATER CONTROL SYSTEM Filed June 23, 1949 3 Sheets-Sheet 3INVENTOR. LINN R BROWN Jl! BY W4- ATTORNEYS Patented Mar. 31, 1953UNITED STATES PATENT OFFICE DAMPER AND HEATER CONTROL SYSTEM Linn P.Brown, J r., Philadelphia, Pa. Application June 23, 1949, Serial No.100,797

Claims.

This invention relates to control systems for heating plants and is moreparticularly adapted to oil burner heating plants of the variety used inhomes.

I have found that it is highly desirable to provide a damper assembly inthe flue of a heating system which permits the chimney to drawrelatively cold cellar air at times when the burner is off. The purposeof this expedient is to prevent excessive cooling of the heating boilerand its associated structure by drawing oif all the heat therefrom.Obviously, such a damper should be automatically controlled so that thestack is substantially closed when the burner is off, and theconstruction of the control system must be adequate to take care of thefirst puff of exhaust gases which takes place when the burner starts, sothat the damper may completely open momentarily. In the normal operatingposition however, the damper is permitted to fluctuate by means of anadjustable balance so that the amount of air drawn from the cellar iscontrolled in accordance with the draft.

A primary object therefore of the invention, is to provide an automaticcontrol system for a damper, whereby the damper shutter is retained in apartially closed position when the burner motor is off but which will beopened by suitable controls when the thermostat calls for heat andbefore the burner circuit is closed.

A further object of the invention is to provide an automatic damper forheating systems in which the damper shutter selectively admits outsideair and products of combustion to the stack.

A still further object of the invention is to provide an automaticdamper assembly for heating systems in which the damper shuttersubstantially closes the flue pipe to the heater when the heater is ofi,and in which the damper shutter is permitted to fluctuate relativelyfree of control and subject to draft conditions in the chimney when theheater is on, to permit selective opening and closing of the flue pipeto the heater and an air passage to the exterior of the flue pipe.

Further objects will be apparent from the specification and drawings inwhich:

Fig. l is a side elevation partly sectioned of a preferred form of mydamper and automatic control mechanism;

Fig. 2 is a schematic diagram showing the damper installed in a heaterand also showing the electrical Wiring connections;

Fig. 3 is an enlarged sectional detail of the control arm and mercuryswitch of Fig. 1;

Fig. 4 is a perspective of a modified form of damper control mechanism;

Fig. 5 is an enlarged sectional detail of the damper of Fig. 4;

Fig. 6 is an enlarged sectional detail of the damper of Fig. 1;

Fig. 7 is a detail showing the damper of Figs. 4 and 5 employed in anelbow rather than a straight through installation; and

Figs. 8-11 are diagrammatic illustrations of successive positions of adamper control system constructed in accordance with the invention.

The invention comprises essentially the provision of an improved damperassembly for the ,flue pipe or stack of a heating system. The

damper assembly is characterized by a shutter which is pivotally mountedin the damper so that in one extreme position the shutter completely orsubstantially closes the flue pipe between the damper and the burner. Inthis position, an aperture through which cold air from outside the fluepipe may enter the stack is completely open. In the other extremeposition of the shutter, the cold air aperture is closed and the fluepipe to the heater is open to permit free passage of the products ofcombustion to the chimney. The damper is automatically controlled bymeans of either a solenoid or an electric motor in cooperation with aheat-responsive thermostat so that when the burner or stoker (as thecase may be) is shut off, the shutter will be pivoted to one positionand when the burner is on, the shutter will be permitted to fluctuatebetween two extreme positions in accordance with the draft present inthe chimney. Throughout the description, the term burner will beemployed in referring to the fuel feeding device for the heater. It willbe understood however, that the invention is adaptable to either liquidor solid fuel feeding means which are electrically controlled.

Referring now more particularly to Figs. 1-3, the damper assembly l5comprises a boxlike housing It having four apertures ll, l8, l9 and 20which are preferably of a size adapted to connect with conventionalstovepipe sizes. In the showing of Fig. l, aperture I8 is connected topipe 2! which leads to the chimney or stack (not shown). Aperture i9 isconnected to pipe 22 which leads to the heater 23. In the form of Fig.l, aperture I! is provided with a removable cap 2t whereas aperture 20is provided with a screen 25. A shutter 28 is pivoted in housing Hi onshaft 21 in such a Way that in one extreme position shutter 26 isadapted to close aperture 20 as shown in broken lines in Fig. 1, whereasin the opposite extreme position shutter 26 abuts a limit stop 28 tosubstantially close pipe 22. The position of limit stop 26 may belocated in accordance with individual requirements and may ermit theshutter 26 to completely close pipe 22 or any desired proportionthereof. Shaft 21 is mounted in housing I6 by means of suitable bearingsand extends on one side of the housing to accommodate an actuating lever29 and arm 3|) having an adjustable threaded counterweight 3| in theform of a collar. Arm 29 is connected to the shutter actuating deviceindicated generally at 32 by means of a flexible connection such aschain 33.

In the preferred form, the shutter actuating mechanism comprises asolenoid 34 having an armature 35 adapted for axial movement within thesolenoid. Armature 35 is connected with a chain 36 which extends arounda sprocket 31 rotatably mounted on shaft 38 supported in housing 39a ofthe actuating device by bracket 39 and nuts 40, 40. One end of chain 36is anchored to housing 39a through a helical extension spring 4| andadjustable eye 42.

The sprocket 31 is rigidly attached to an arm 43 by means of screws 43a,43a, and the arm 43 is connected to the upper end of chain 33 by a link33a, as seen in Fig. l. Upward pivotal movement of arm 43 is limited bymeans of an enlarged ring 44 in chain 33 which seats against the grommet45, the bore of which is smaller in diameter than ring 44. Arm 43 alsocarries a mercury switch 46 attached to the arm by means of bracket 41and bolt 48. Electrical leads 49 and 50 connect the mercury switch 46 toa junction block within the housing 390,. Likewise, solenoid 34 isconnected to junction block 5| by means of leads 52 and 53. Current toswitch 46 as well as for solenoid 34 is carried to block 5| throughleads 54, 55 and 56 as shown clearly in Fig. 1.

To describe the operation of my control, let it be assumed that burner60 is ofi. Under this condition, shutter 26 is in the relatively closedposition against the limit stop 28 and lever arm 29 is consequentlyraised by the tension of spring 4| acting through chain 36, sprocket 31and arm 43. Solenoid 34 is of course, deenergized in this case andmercury switch 46 is open. When thermostat 6| calls for heat, theelectrical circuits function in accordance with conventional practiceexcept that the power connection to burner 66 is fed through mercuryswitch 46 by means of leads 49 and 50.

Fig. 2 illustrates the wiring diagram for operating the damper controlunit 32. A source of power 62 is connected to burner motor 63 throughlead 64. The other lead 65 from power source 62 is connected to theconventional stack control 66 in the customary manner. The solenoid 34is connected in series with the output lines 54 and 55 from the stackcontrol 66 so that when the stack control 66 is closed, the burner motor63 will not start until the circuit through leads 54 and 55 is completedby clockwise pivoting of arm 43, as will be described hereinafter. Lead69 connecting the burner motor and the stack 66 is for ignition. Assolenoid 34 becomes energized through proper action of the thermostat 6|and stack control 66, armature 35 is retracted within solenoid 34 whichin turn drops arm 43 to the broken line position shown in Fig. 1. As thearm drops, mercury switch 46 closes the circuit through leads 54 and 55,thus starting burner motor 63. However, the timing of the system is suchthat switch 46 does not start motor 63 until the arm 43 is in a nearlycompletely lowered position. This permits the shutter 26 to pivotupwardly and thereby close aperture 20 during the first rush of exhaustgases from the heater 23 which customarily takes place when the burnerignites.

With arm 43 in the fully lowered position, there is sufilcient slack inchain 33 to permit the shutter 26 to return to an intermediate position,such as that shown in broken lines in Fig. 1. So long as the solenoid 34is energized, there is no control of the position of shutter 26 throughchain 33. Therefore, with the burner 69 operating, the shutter is freeto fluctuate in the damper housing 6| in accordance with the draftconditions present in the stack. The adjustment of nut 3| regulates theintermediate position of the shutter so that any desired ratio betweenoutside air and stack gases may be provided. Likewise, the position ofnut 3| controls the amount of slack in chain 33 in accordance with theangular relationship between shutter 26 and lever 29.

Referring now to Figs. 4-6, a straight-through damper assembly H6 isshown connected to flue pipe III leading to the heater and to pipe H2,leading to the chimney or stack in the same manner described inconjunction with Figs. 1-3. Likewise, damper assembly H0 is providedwith aperture |I3 communicating with pipe H2, and aperture I I4communicating with pipe III. Aperture I|5 has a cap II6 which supports ascreen I1 through which outside air is permitted to enter the stack, andaperture ||5a has a cap II6a which may be removed for clean-outpurposes. Shutter I I8 is mounted on shaft I I9 which is in turnjournaled in ball bearings I20 in the damper housing. A stop |2I ispositioned in the damper assembly and functions in the same mannor asdoes stop 28 in Fig. l. Shaft ||9 extends through the damper housing andhas an actuating lever I22 secured to a splined end of shaft II9 bymeans of set screw I23. Arm I22 carries a rod I24 on which a pluralityof counterweights I26 may be selectively positioned in order to providesuitable adjustment for shutter H8. The opposite end of shaft I I9 isprovided with a lever arm I26 which is similar to the arm 29 of Fig. l.

The shutter actuating mechanism comprises an actuating motor I30 mountedon a panel |3| so that one arm |32 of the motor is substantially abovethe end of lever I26 on damper IIO. Arm I32 of the motor is connected tolever I26 by means of a chain I33 or other flexible connection.

Arm I32 is also spring-loaded upwardly by means of helical extensionspring I34 attached to the ceiling or other fixed member I35. Theopposite motor arm I36 is operatively associated with an arm I31 of amercury switch assembly I33 which is rotatably mounted on a panel I33. Achain 40 serves to connect arms I36 and I31. It will be understood thatmotor I39 may, if desired, be of any variety well known in the art, anexample of which is the type M-87A motor supplied by theMinneapolis-Honeywell Regulator Company. Motor I36 is connected to theusual house current source I45 through transformer I46 and electricallines 141 and I48. Lines I49 and I5!) connect the motor to thethermostat (not shown). Lines |5| and I52 connect to the oil burnermotor (not shown) through a suitable relay (not shown) for the purposeof stopping and starting the burner, substantially as describedpreviously.

The operation and timing of both systems will 51' be more clearlyunderstood from the following description which is intended to relateeither to the motor controlled device of Fig. 4, or the solenoidactuated device of Fig. 1. Let it be assumed that the burner motor hasbeen previously shut off by the thermostat. The relative positions ofthe control system elements is then illustrated by Fig.4 in which armI28 is raised to its upward limit as are likewise arms I32 and I316 ofthe motor I33. In the schematic illustration of Figs. 8-1'1, arm I35operates in the reverse vertical direction from arm I32 whereas in theshowing of Fig. 4, arms I32 and I36 work simultaneously in the samedirection, the only difference being that the arm I37 for mercury switchI38 will be located on the opposite side of the switch in order toprovide the desired functioning for switch I38.

When the thermostat circuit in leads I49 and I!) is closed, motor I33starts and arms I32 and I31 are gradually lowered (shown by the arrow inFig. 4). In this cycle, arm I31 will be raised in the showing of Figs.8-11. When arm I22 and shutter H8 are pivoted to the position shown inFig. 9, the counterweight I25 balances the shutter I I8 so that with theburner still off, the shutter and its associated arm's I22 and I 2e willremain in the position of Fig. 9 which corresponds to the intermediatebroken line position of Fig. 5. Motor I32 however, continues to lowerarms I32 and I36 until the mercury switch is in the approximate positionshown in Fig. 10. At this point, there is substantial slack in chain I33and the position of switch I33 in Fig. shows the mercury an instantbefore closing the circuit in lines I5I and I52 to the burner motor. Itwill be apparent that adjustment of the balanced position of the shutterwhich in turn controls the amount of slack in the chain at the time theburner starts, may be adjusted by means of counterweights I and thesplined connection between shaft H9 and levers I22 and I 26.

When the burner motor circuit is closed, there is a momentary rush ofgases in the stack which occurs upon starting of the burner. When thishappens, shutter I I8 is forced upwardly as shown in Fig. 11, but theamount of slack in chain I33 is suificient to permit the shutter tocompletely close opening II5 in the damper assembly II 8. It isimportant therefore, that the burner circuit remain open until there issufficient slack in the damper control means to permit the shutter toswing to the position of Fig. 11. After a few seconds, the gas pressurein the stack decreases, thus permitting shutter II8 to partially openthe cold air intake II 5. Such position corresponds approximately to theintermediate broken line position of Fig. 5 in which the shutter isautomatically regulated by the draft in the stack.

As long as the thermostat calls for heat, motor i3Il will be energizedor otherwise locked so that chain I33 is slack and spring I34 extended.When the thermostat is satisfied however, the locking means for motorI35] is released to enable spring I34 to return the damper and mercuryswitch to the original position of Fig. 4. In this return cycle, it isimportant that the burner motor be stopped before the chain I33 becomestaut. Therefore, the adjustment of arm I 22 and the amount of slack inchain I33 are carefully proportioned so that the circuit between leadsI5I and IE2 is broken for an appreciable length of time before theshutter I I 8 is fully lowered. Fig. 9 also illustrates this conditionand clearly shows that the burner circuit is opened by mercury switchI38 at about the time chain I33 becomes tauta'nd substantially beforethe shutter I I8 pivots to the off" position.

It will therefore be apparent that a damper control system in accordancewith the present invention is relatively inexpensive to manufacture, iscompletely automatic in all respects, and is so constructed that allsafety requirements are met by proper timing of the burner motor withthe action of the damper.

Having thus'described my invention, I claim: 1. In a control system foran automatically fired furnace having a stack connecting the combustionchamber of the furnace to a chimney, a damper housing located in saidstack between the furnace and the chimney, walls defining an exthechimney and covering said external opening, actuating means for pivotingthe shutter from said second position to said first position, electricmotor operated heating means for the furnace, an electrical controlcircuit for the motor of said ment of the actuating means, a chain-likeelebetween the actuating means 2. A control system in accordance withclaim 1 in which the actuating means includes a motor having a pair ofarms, the first of said arms being connected to the when saidthermally-responsive switch opens to stop the motor of said heatingmeans.

3. A control system in accordance with claim 1 in which the actuatingmeans includes a solenoid,

arm to an initial position with "re shutter in said first position andsaid second switch open when said solenoid is 'deenergized.

4. A control system in accordance with claim 1 in which the shutter ismounted on a shaft extending through the damper arm having one endconnected to said shaft and its other end connected to said drain-likeelement, and means on said arm and shaft for regulating the effectivelength of the said chain-like element.

5. A control system in accordance with claim '1 in which the shutter ismounted on a. shaft pivoted in the damper housing, with a first armadjustably connected to one end of said shaft, a. counterweight on saidfirst arm, and a. second arm adjustably connected to the other end ofsaid shaft and connected to said chain-like element.

LINN P. BROWN, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

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